Apparatus for handling shrinkable material

ABSTRACT

Apparatus for conveying an elongated component, characterized by being shrinkable upon being heat treated, providing for the support and passage of the elongated component in a sinuous configuration to compensate for shrinkage upon heating, and for utilization of heating means of short length.

United States Patent Fenner BEST AVAILABLE copy [45] July 25, 197 2 [541APPARATUS FOR HANDLING SHRINKABLE MATERIAL [56] References Cited [72]Inventor: James M. Fenner, Niles, Mich. UNITED STATES PATENTS [73]Assignee: National-Standard Company, Niles, Mich. 2,938,234 5/1960 Sladel 8/55 [22] Flled: 1971 Primary Examiner-Gerald A. Dost [21] Appl. No.:106,714 Attorney-Johnson, Dienner, Emrich, Verbeck & Wagner Related US.Application Data 57 ABSTRACT Continuum-impart of March 14, Apparatus forconveying an elongated component, charac- 1969, abandonedterized bybeing shrinkable upon being heat treated, providing for the support andpassage of the elongated component in a U.S. Cl. R, sinuou onfigurationto compensate for shrinkage upon heat. [5 i 1 Int. Cl. i t i and forutilization of heating means ofshon length [58} Field oi Search....266/2, 2.5, 3; 72/257, 263;

75/211, 214, 223, 224, 227 11 Claims, 9 Drawing figures 10 12 ll 13 1*"-51 F 1Q I 2 I I I 30 A PFENTED JUL 25 I972 sum 1 0F 3 jnuenlb r."Jamesfffnner,

APPARATUS FOR HANDLING SI-IRINKABLE MATERIAL This application is acontinuation-in-part of my co-pending application, Ser. No. 807,391,filed Mar. 14, 1969 and now abandoned.

BACKGROUND In the fabrication of elongated articles, such as wire,tubing and strip formed, for example, by forming means such as anextruder for extruding metal compound compacts which are characterizedby being ductile when discharged from the extruder but become fragilewhen heated and subject to shrinking when reduced and/or sintered, thethe use of a conventional endless belt type conveyor for conveying theextrusion in a straight continuous length through the reducing andsintering furnaces is not practical. in that the extrusion when subjectto heat becomes fragile and when reduced and/r sintered it shrinks,simply supporting a straight extrusion on a conventional endless beltconveyor, due to relative linear movement of the extrusion with respectto the surface of the belt, may result in creating imperfections in orfracturing of the reduced and/or sintered extrusion. Also, due to timerequirements for reducing and/or sintering with extruded material laidin a straight continuous length on the upper run of a conventional beltconveyor would necessitate a furnace of substantial length so as to beuneconomic from both space and furnace costs standpoints.

Typical of extruded metal compound compacts with which the apparatus ofthe invention may be employed were produced in the following manner. Theby-product iron oxide, from spent pickle recovery was milled in aconventional manner until 50 percent of the iron oxide particles wereless than eight-tenth microns in major dimensions, and 50 percent beingin a range of from eight-tenth microns to 10 microns. A binder was thenprepared by adding 15 grams of corn starch to 100 milliliters of waterand heating the solution to 160 F. until a gel was formed. 4.2 grams ofthis binder was then added to 22.7 grams of the milled iron oxide powderand the combination was then mixed intimately in the mix-mullet. Themixture of iron oxide and binder was then put into the cavity of anextrusion die having an opening of 0.115 inches in diameter and apressure of 12,000 psi applied which formed a green metal component.This green metal component was then conveyed by the apparatus of thepresent invention into a furnace having a reducing section providing anatmosphere of hydrogen at a temperature of about 1,000 F. for a periodof 5 minutes, and then a sintering section at which the temperature wasraised to 2,100 F. and remained at this temperature for 5 minutes duringwhich time sintering was completed.

The apparatus of the present invention also has utility for utilizationwith tubing formed from a green metal component made from the sameformulation as the wire component above described but extruded through aconventional tube forming die to form, for example, a tubular greenmetal component having an outside diameter of 0.115 inches and aninternal diameter of 0.065 inches. Such tubing was then conveyed by theconveyor apparatus of the present invention through the reducing andsintering areas of a furnace in which the tubing was maintained in ahydrogen atmosphere at a temperature of 1,1 F. for 8 minutes to effectreduction of the green metal tubular component. The reduced tubing wasthen subjected to sintering in the sintering section of the furnace at atemperature of 2,l00 F. for a period of 5 minutes.

In the two examples given for wire and tubular members, the reduced andsintered wire and tubing undergo lineal shrinkage of about 30 to 40percent.

The apparatus of invention also has utility for use with elongated greenmetal components formed by forming means other than an extruder. By wayof example, elongated components of metal compound compacts may beformed into green preforms for elongated components by depositingslurry-like metal compound compacts upon forming means having a surfacein which one or more longitudinally extending grooves are formed forreceiving the slurry material so that the slurry material is shaped toform one or more elongated components and set therein. The grooves ofthe forming means are fabricated of material from which the shaped andset material in the grooves may be easily separated from the grooveswithout fracturing the shaped and set material, and the reducing and/orsintering the shaped and set material as aforedescribed.

The slurry material for the purposes last noted may be composed, inpart, of a reducible metal compound such as metal oxide powder which maybe reduced and sintered to provide metal wire. The metal oxide compoundpowders of the slurry material may comprise oxide particles of which atleast 35 percent are of a particle size of 10 microns or less asdetermined by Coulter Counter Analysis. Thus the particle sizedistribution will be considerably below the maximum 35 percent under 10microns, and may have a mean particle size no greater than about 6microns and at least 25 percent by weight, the particles will be below2.5 microns in diameter. Optimum results are obtained when the apparentaverage particle of the powder is less than 1 micron in diameter.

That the average particle is less than 1 micron in diameter may bedetermined by Coulter Counter measurement where agglomeration is not afactor. However, where the particles tend to agglomerate, accurateparticle size determination by means such as Coulter Counter measurementis not possible. It has been found, however, that such determination maybe made by surface area determination. By determining the total surfacearea of a given powder one can readily determine the average particlesize if one assumes perfectly smooth, spherical particles. Suchdetermination may be made through the utilization of the formula:

D= (IO/(d X SA) where,

D== average diameter in microns of perfect spheres K the constant 6 ddensity in grams per cubic centimeter SA =surface area of the particlesin square meters per gram.

For example, if one determines the surface area of iron oxide Fe,0, tobe 5 m Ig and the density to be 5.24 g/cc then:

D=0.23 microns There are a number of known means for determining thesurface area of powders each differing to some extent in results. It isfound that the BET method developed by Dr. Paul Emmet and his associatesin the late 1930's for use in measuring the available surface area ofcatalysts to be the most reliable for determining the surface of metalcompound powders.

In the BET method the surface of the particles is coated with amonomolecular layer of adsorbed gas. This is accomplished by passing aknown quantity of gas, such as nitrogen, through a measured specimen atthe boiling point of the gas (C. for nitrogen). Under these conditionsthe gas molecules form a tightly packed monomolecular layer on thesurface of the specimen. A determination of the gas consumed by thespecimen by monomolecular adsorption as compared to standard specimensreadily yields a relatively accurate determination of the surface areaof the powder.

For purposes of the foregoing, particle size determination of less than1 micron shall be interpreted in accordance with BET measurements.

A suitable slurry material for forming continuous elongated green metalcomponents may be composed of the aforementioned Oxide powders togetherwith a binder to provide the slurry material of a consistency to enablethe ready deposit of the slurry material onto a grooved belt. A typicalbinder for iron oxide powder of the particle size range aforenoted maybe a PVA-glycerine binder composed of a mixture of polyvinyl alcohol andglycerine in a 80 to 20 ratio mixed with the oxide powder to provide aslurry material of a consistency enabling its deposition onto theforming means as described to fill the grooves in the forming means onthe belt.

Upon deposition of slurry material as aforenoted the separated and setgreen metal elongated components are subjected to reduction andsintering to form elemental wire. Typically, the separated and set greenmetal elongated components may be suitably passed through a reductionand sintering furnace in which the reduction is effected in anatmosphere of hydrogen at about l,000 F. for 5 minutes, and sintering ata temperature of about 2,l F. for about minutes. It will be understoodthat the reduction and sintering time is dependent on the size andcross'section of the material being treated.

In addition to the foregoing example of a slurry material suitable forfabricating metal wire, it will be understood that the apparatus of thepresent invention is applicable to any reducible metal compound,particularly those susceptible to reduction with hydrogen which havestandard free energies of reaction with hydrogen less than about kilocalories (per atom) of hydrogen at the reduction temperature. The metalcompounds of particular interest in connection with the foregoing arethe metal oxides such as the oxides of Fe, Co, Ni, Cu, Mo, and W, andcombinations thereof.

Although the use of hydrogen to provide the environment for reducing theforegoing slurry materials to elemental metal is preferred, otherreducing materials may be employed. For example, the above recited metalcompounds, and particularly iron oxide, can be reduced by partially orwholly substituting carbon monoxide for the hydrogen reducingenvironment.

Any metal compound powders having particles of any general shape (i.e.,spherical, oblong, needles, or rods, etc.) and originated from anysource (i.e., ore deposits, or concentrates, precipitates, etc.) may beemployed in providing the slurry material for the present invention forforming elongated green metal components, for example in the grooves ofan endless belt, and subsequent reduction and sintering.

The sintered elongated components so derived will possess asubstantially pore free structure, a smooth surface and can be made toexhibit densities in excess of 90 percent of completely dense material.

It will be understood that the foregoing examples are only illustrativeof metal compound compacts that shrink when reduced and/or sintered, andthat the apparatus of the present invention has utility for the manyother materials of the class that shrink when reduced and/or sintered.

THE INVENTION The present invention comprehends the formation of anelongated component of a metal compound compact characterized by beingshrinkable upon heating thereof. The formed elongated green metalcomponent is then conveyed in a sinuous configuration through a heatingfurnace with the sinuous configuration of the elongated componentenabling the utilization of heating means of short length. Importantly,the elongated component of sinuous configuration may lie in successivelysupported loops in a vertical plane in the heating means which allowsfor the progressive longitudinal shrinkage of the elongated green metalcomponent when subjected, for example, to reducing and then sintering.In forming the elongated component into sinuous configuration, and uponpassage through the furnace means the successive loops progressivelybecome smaller and this change in dimension is compensated for accordingto the invention without danger of fracture or cracking of the elongatedcomponent, and further prevents any disruption of the surface of theelongated component in that no substantial force opposes shrinkage ofthe elongated component.

BRIEF DESCRIPTION OF THE DRAWINGS F 1G. I is a side elevational view ofone form of apparatus of the invention;

FIG. 2 is a plan view of the apparatus of FIG. 1;

FIG. 3 is an end elevational view of the apparatus shown in FIGS. 1 and2;

FIG. 4 is a detail vertical sectional view taken substantially along theline 4-4 of FIG. 1 looking in the direction indicated by the arrovts;

FIG. 5 is a diagrammatic perspective view of a second form of apparatusof the invention;

FIG. 6 is a side elevational view diagrammatically illustrating thesupport and drive means for the conveyor shown in FIG. 5;

FIG. 7 is an end elevational view of the apparatus shown in FIG. 6;

FIG. 8 is a side elevational view of a third form of apparatus of theinvention; and

FIG. 9 is a plan view of the apparatus of FIG. 8.

As seen in FIG. 1, the apparatus there shown comprises forming means,such 'as an extruder, indicated by the reference numeral 10, furnacemeansll which may be a two section furnace comprising a reducing area 12having conventional heating means 34 and reducing gas supply means 35,for supplying a reducing gas such as-hydrogen or carbon monoxide to thereducing area, and a sintering area 13 provided with conventionalheating means 36, and conveyor means 14 for receiving continuouselongated components such as extrusions from the extruder for conveyingthe extrusions through the furnace means 11 to effect, in theillustrated embodiment, reduction of the extrusions followed bysintering of the extrusions.

The extruder 10 supported as at 10' is of conventional construction andpreferably is provided with a plurality of die discharge openings todischarge a plurality of continuous elongated extrusions, as at A, inside-by-side relation onto the conveyor l4 forpassing through thefurnace means 1 1. Of course, if desired the extruder could be of aconstruction to discharge a single continuous extrusion but for economicpurposes it is desirable to provide for the discharge of severalextrusions.

The conveyor means 14 comprises spaced apart end sprockets 15-15 and16-16 keyed to shafts 18 and 19, respectively, mounted on bearing blocks20 and 21, respectively. The shaft 18 is provided with a drive gear 22connected by a drive chain 23 to the output gear 24 of a prime mover 25.The conveyor means 14 further comprises a pair of endless laterallyspaced apart ropes 26 of high temperature resistant material, such asInconel, which as best seen in FIG. 4 pass through and are secured inthe slotted ends at a plurality of transversely extending pins 30disposed in uniform spaced apart relation lengthwise of and between thespaced apart ropes 26. Guide rails 32 lying inwardly of the side wallsof the heating furnace means 11 are engaged by the pins 30 to supportthe upper run of the conveyor in passing through the furnace means 11.

The sprockets 15-15 and 16-16 are formed with pin receiving recesses 33into which the pins 30 are disposed in movement of the conveyor.The-prime mover 25 thus provides for driving of the sprockets 15-15andtogether with the engagement of the pins 30 in the pin receiving grooves33 provides for driving of the conveyor with the upper run of theconveyor passing from the sprockets 15-15v toward the sprockets 16-16 atthe discharge end of the apparatus.

As best seen in FIG. 1, the extruder 10 is discharging forwardly offurnace means 11 a plurality of spaced apart sideby-side continuouselongated extrusions A upon one of the pins 30. Upon movement of theupper run of the conveyor from the inlet end of the furnace means 11 tothe outlet end thereof, it will be observed that the extrusions aresupported in continuous sinuous configuration between adjacentsupporting members 30. Upon initial passage of the conveyor into thereduction section 12 of the furnace means 11, the extruded material iscaused to be chemically reduced and as the upper run of the conveyorprogresses through the furnace means I I, the continuous configurationsof the extrusions form loops of smaller dimension and with suchreduction of the material continuing upon passage of the continuouselongated extrusions through the sintering section 12 of the furnace.The extrusions after passing through the sintering section of thefurnace will be of substantially less linear length than when first fedonto the conveyor at the extruder 10. As will be noted, the continuouselongated extrusions A are of sinuous configuration and lie in verticalplanes longitudinally of the direction of travel of the upper run of theconveyor means 14.

The afore described apparatus thus provides for the disposal of anelongated extrusion from an extruder onto conveyor means in a manner toprovide for a sinuous configuration to the extrusion and which extrusionas it progresses through the furnace means 11 forms pRogressive loops ofsmaller dimension due to the shrinkage of the material when subjected toreduction and sintering.

Referring now to FIGS. 5 through 7 there is shown a second embodiment ofthe invention. In FIG. 5 it will be observed that the apparatus thereshown comprises a plurality of endless belts 40, again' of a heatresistant material such as Inconel, disposed in side-by-side relationfor passage through heating means 42 having a reducing section 43 and asintering section 44.

An extruder 45 serving as a forming means is supported in any suitablemanner above the upper runs of the several belts 40 for reciprocatorymovement transversely of the upper runs of the belts 40. Conventionalreciprocating mechanism 46 is provided to reciprocate the extrudertransversely of the upper run of the several belts 40. If desired, theextruder could be fixedly mounted and the conveyor reciprocatedtransversely thereto. The extruder 45 may be of conventionalconstruction provided at its discharge end with a die opening todischarge a single continuous elongated extrusion as at B which whenreciprocated relative to the upper runs of the several belts 40 disposesthe continuous length of extruded material B into loops between theseveral belts 40 which lie substantially in vertical planes transverselyof the direction of travel of the several belts 40. Again, as theextruded material laid upon the belts in the manner above describedpasses through the reducing area 43 with which heating means 58 andreducing gas supply means 59 are associated and through the sinteringarea 44 heated by heating means 60 it shrinks substantially, so that theloops of the extruded material become progressively smaller as thematerial passes from the extruder out through the discharge end of thefurnace 42.

The several belts 40 as seen in FIGS. 6 and 7 may at the ends thereofforwardly of the extruder 45 be supported on guide idler rollers 50, andwith the several belts being looped about a driving drum 52 formed witha plurality of grooves to receive each of the belts 40. A drive gear 52connected with the common driving drum 52 is driven by means of a chain53 extending to an output gear 54 of a prime mover and gear reducerassembly 55. Thus upon energization of the drive unit 55, the drive gear54 through belt 52 engaging with gear 52' effects rotation of the commondrive drum 52 to provide for passage of the several belts 40 in aclockwise direction as viewed in FIG. 6. If desired, the lower portionsof the upper run of the several belts 40 may be supported by flexiblesupporting means as diagrammatically indicated at 56 to support theupper runs of the belts 40 in passing through the furnace means 42.

The apparatus shown in FIGS. 8 and 9 embodies conveyor means 14' andfurnace means 11' which are the same in all essential respects asconveyor means 14 and furnace means 11 described in connection withFIGS. 1 through 4, except being of greater width to accommodate agreater number of elongated components or filaments for processing, andthe primed reference numerals applied to FIGS. 8 and 9 indicate the sameparts as described in connection with FIGS. 1 through 3 but being ofappropriate size where required to take into account the greater widthof conveyor means 14 and fumAce means 1 l In FIGS. 8 and 9 there isillustrated an apparatus embodying forming means 70, in lieu of anextruder as shown in FIGS. 1 through 3, for forming and deliveringelongated components of a metal compound compact as aforedescribed toconveyor means 14. The forming means 70 may, by way of example, be inthe form of an endless belt means 72 mounted between a pair of spacedapart end roller means, only one of which is shown at 73, which mayconstitute a drive roller means for the endless belt 72 which may bedriven by a drive chain 74 extending between the drive roller means 73for the belt 72 driven ofl of the drive gear 75 keyed to shaft 18 of theconveyor means 14. The drive means described thus provides for effectinglongitudinal movement of the upper run 76 of the endless belt 70 fromleft to right as viewed in FIGS. 8 and 9. The endless belt means 70 isformed with a plurality of indentations defined by spaced apartcircumferentially continuous grooves 78 which may be of any desiredcross sectional configuration.

Hopper means 80 is suitably supported above the upper run 75 ofthe,,endless he]; means 70 by conventional means, not shown, fordepositing the aforementioned metal compound compact material upon thebelt for filling the grooves in the belt. Doctor blade means 82 may besupported in any suitable manner downstream from the hopper means 80 toassure filling of the grooves with the metal compound compact material.

Downstream of the doctor blade means 82 of the upper run 75 of theendless belt 70 passes through heating means 83, such as a conventionalheating oven, so as to set the material in the grooves of the endlessbelt when such heating is required for setting. After passage of theupper run of the endless belt 70 through the heating means 83, the setmaterial in the grooves is discharged from the endless belt means 70 atits discharge end and passed therefrom onto the conveyor means 14' inwhich the elongated green metal components are then processed asdescribed in connection with FIGS. 1 through 4.

Thus it will be seen in the apparatus of FIGS. 8 and 9 that a largenumber of circumferentially continuous spaced apart grooves may beformed in the endless belt means 70 to provide for the passagelongitudinally of a plurality of elongated green metal componentsthrough the furnace means 1 l.

The endless belt means 70 is preferably fabricated of a material fromwhich the formed and set green metal elongated components may be readilyseparated from the grooves without fracturing, for example, a materialhaving low adhesive characteristics, such as Teflon or polyethylene.

It will be understood from the foregoing that the invention embodiesapparatus as shown and described in connection with FIGS. 1 through 4and FIGS. 8 and 9 in which one or more elongated continuous componentsare discharged from forming means into sinuous configuration in avertical plane in the direction of travel of the conveyor through aheating furnace having reducing and sintering areas. In the apparatusdescribed in'connection with FIGS. 5 through 6, continuous elongatedmetal components are discharged transversely of the direction of themovement of the conveyor to dispose the material in sinuousconfiguration lying in planes substantially transverse to the directionof travel of the conveyor through a heating means.

The invention claimed is:

1. An apparatus for heat treating an elongated extrusion which ischaracterized by being shrinkable upon heat treating thereof comprisingfurnace means having reducing and sintering means for reducing andsintering the extrusion, an extruder for extruding the elongatedextrusion, conveyor means for receiving the elongated extrusion fromsaid extruder and conVeying the extrusion through said furnace means,and supporting means for said conveyor means for supporting theextrusion in a sinuous configuration while being conveyed through saidfurnace means.

2. The apparatus of claim 1 characterized by said supporting meansproviding for supporting the extrusion in a vertical planelongitudinally of the direction of travel of said conveyor means.

3. The apparatus of claim 1 characterized by said supporting meansproviding for supporting the extrusion in a vertical plane transverselyof the direction of travel of said conveyor means through said furnacemeans.

4. The apparatus of claim 3 characterized by the provision of means foreffecting reciprocating movement of said extruder transversely of saidconveyor means.

5. The apparatus of claim 2 in which said supporting means comprises aplurality of supporting means extending transversely of the direction oftravel of the extrusion through the furnace.

6. The apparatus of claim 3 in which said supporting means comprises aplurality of endless conveyor members disposed in side-by-siderelationship extending longitudinally in the direction of travel of theextrusion through the heating furnace.

7. An apparatus for heat treating an elongated component which ischaracterized by being shrinkable upon heat treating thereof comprisingfurnace means having reducing and sintering means for reducing andsintering the elongated component, forming means for forming theelongated component, conveyor means for receiving the elongatedcomponent from said forming means and conveying the elongated componentthrough said furnace means, and supporting means for said conveyor meansfor supporting the elongated component in a sinuous configuration whilebeing conveyed through said furnace means.

8. The apparatus of claim 7 characterized by said supporting meansproviding for supporting the elongated component in a vertical planelongitudinally of the direction of travel of said conveyor means.

9. The apparatus of claim 7 characterized by said supporting meansproviding for supporting the elongated component in a vertical planetransversely of the direction of travel of said conveyor means throughsaid furnace means.

10. The apparatus of claim 8 in which said supporting means comprises aplurality of supporting members extending transversely of the directionof travel of the elongated component through the furnace means. 7

11. The apparatus of claim 9 in which said supporting means comprises aplurality of endless conveyor members disposed in side-by-siderelationship extending longitudinally in the direction of travel of theelongated component through the furnace means.

1. An apparatus for heat treating an elongated extrusion which ischaracterized by being shrinkable upon heat treating thereof comprisingfurnace means having reducing and sintering means for reducing andsintering the extrusion, an extruder for extruding the elongatedextrusion, conveyor means for receiving the elongated extrusion fromsaid extruder and conVeying the extrusion through said furnace means,and supporting means for said conveyor means for supporting theextrusion in a sinuous configuration while being conveyed through saidfurnace means.
 2. The apparatus of claim 1 characterized by saidsupporting means providing for supporting the extrusion in a verticalplane longitudinally of the direction of travel of said conveyor means.3. The apparatus of claim 1 characterized by said supporting meansproviding for supporting the extrusion in a vertical plane transverselyof the direction of travel of said conveyor means through said furnacemeans.
 4. The apparatus of claim 3 characterized by the provision ofmeans for effecting reciprocating movement of said extruder transverselyof said conveyor means.
 5. The apparatus of claim 2 in which saidsupporting means comprises a plurality of supporting means extendingtransversely of the direction of travel of the extrusion through thefurnace.
 6. The apparatus of claim 3 in which said supporting meanscomprises a plurality of endless conveyor members disposed inside-by-side relationship extending longitudinally in the direction oftravel of the extrusion through the heating furnace.
 7. An apparatus forheat treating an elongated component which is characterized by beingshrinkable upon heat treating thereof comprising furnace means havingreducing and sintering means for reducing and sintering the elongatedcomponent, forming means for forming the elongated component, conveyormeans for receiving the elongated component from said forming means andconveying the elongated component through said furnace means, andsupporting means for said conveyor means for supporting the elongatedcomponent in a sinuous configuration while being conveyed through saidfurnace means.
 8. The apparatus of claim 7 characterized by saidsupporting means providing for supporting the elongated component in avertical plane longitudinally of the direction of travel of saidconveyor means.
 9. The apparatus of claim 7 characterized by saidsupporting means providing for supporting the elongated component in avertical plane transversely of the direction of travel of said conveyormeans through said furnace means.
 10. The apparatus of claim 8 in whichsaid supporting means comprises a plurality of supporting membersextending transversely of the direction of travel of the elongatedcomponent through the furnace means.
 11. The apparatus of claim 9 inwhich said supporting means comprises a plurality of endless conveyormembers disposed in side-by-side relationship extending longitudinallyin the direction of travel of the elongated component through thefurnace means.